Method for controlling viscosity of organic liquids and compositions thereof

ABSTRACT

A method for controlling the viscosity of organic liquids, said organic liquid having a solubility parameter of less than 9.5, a viscosity, as measured at 25° C., of less than 200 centipoises and said organic liquid is selected from the group consisting of mineral oils, synthetic oils, naphthanes, alkanes, cycloalkanes and aromatics and mixtures thereof, which comprises incorporating in said organic liquid about 0.01 to 20 grams of polymer complex per 100 ml. of said organic liquid, said polymer complex being formed &#34;in situ&#34; in said organic liquid or dissolved in said organic liquid, said complex being comprised of polymer A, containing about 4 meq. to 500 meq. of neutralized sulfonate groups, and polymer B, containing basic nitrogen groups, both functional groups being present at a level of from about 4 to 500 meq. per 100 g. of polymer, wherein polymer B has the formula: ##STR1## wherein x is about 50.0 to 99.8 weight percent and y is about 0.2 to about 50.0 weight percent, wherein said sulfonate groups of said polymer A being neutralized with basic compounds selected from the group consisting of transition elements, said polymer A having a polymeric backbone substantially soluble in said organic liquid and said polymer having a molecular weight of about 1,000 to 10,000,000.

This application is a continuation-in-part application of U.S. Ser. No.720,722, filed Apr. 8, 1985, now U.S. Pat. No. 4,737,534, which is acontinuation-in-part application of U.S. Ser. No. 547,908, filed Nov. 2,1983, now abandoned.

FIELD OF THE INVENTION

The instant invention relates to a process for controlling the viscosityof organic liquids by incorporating in said liquid a minor amount of twointeracting polymers and optionally, a cosolvent for the ionic groups ofsaid polymer. The ionic polymer comprises a backbone which issubstantially soluble in said organic liquid and pendant ionic groupswhich are substantially insoluble in said organic liquid. The otherpolymer contains basic nitrogen atoms such as amine groups whichinteract with the ionic counterion and form a complex. A cosolvent isselected which will optionally solubilize the pendant ionomeric groupsand provide a reasonably homogeneous mixture of solvent, cosolvent andionomeric polymer. The preferred compositions prepared by the method ofthe instant invention comprise an organic liquid having a solubilityparameter of from 6 to 10.5 in combination with a sulfonated polymercontaining from 0.2 up to 10.0 mole % ionic groups which has beenneutralized by a basic material selected from Groups IA and IIA, IB andIIB and also lead, tin and antimony of the Periodic Table of theElements, wherein the sulfonated polymer is complexed with a polymercontaining basic nitrogen atoms such as an amine-containing polymer andoptionally, a non-volatile alcohol or amine as the cosolvent.

BACKGROUND OF THE PRIOR ART

The rapid decrease in viscosity of liquids with increasing temperatureis well-known. Ideally, for many applications (automobile lubricants,etc.) it would be desirable to solve this problem so that viscositywould be insensitive to temperature. Alternatively, it might bedesirable to provide liquid systems whose viscosities actually increasewith temperature. It is true that with selected polymeric additives, ithas been possible to reduce substantially the viscosity change withtemperature which does occur with most oils and similar systems. Thesepolymer additives, known as viscosity index improvers (or V.I.Improvers) are generally high molecular weight polymers.

The way in which these additives function can be summarized verybriefly. In effect, they perform two functions, i.e., thickening, whichmerely increases fluid viscosity; and Viscosity Index (V.I.)improvement, which corresponds to limited thickening at ambienttemperatures and a correspondingly greater thickening at elevatedtemperatures. This can be accomplished by utilizing a polymeric additivewhich is poorly solvated by the liquid at ambient temperatures; however,at elevated temperatures the polymer is more highly solvated such thatthe polymer expands and is a relatively more effective thickener.

While these V.I. Improvers have proven successful commercially, it isimportant to note that their effect at reducing viscosity changes withtemperatures is rather mild. For a typical base oil containing asuitable V.I. Improver, the kinematic viscosity will still decrease by afactor of from 5 to 10 as the temperature increases from 30° to 100° C.Obviously, if it is desired to hold the viscosity roughly constant withsuch temperature changes, current technology has not offered anappropriate additive system.

U.S. Pat. No. 3,396,136 describes how copolymers of alkenyl aromaticsulfonic acids, when properly neutralized, can be employed as thickenersfor nonpolar solvents. Those metal sulfonate systems have been shown tobe very effective; however, when employed as two component systems(i.e., ionic polymer plus nonpolar solvent), the variation of viscositywith increased temperature is very conventional and predictable. Thatis, the solution viscosity decreases markedly as temperature isincreased.

U.S. Pat. No. 3,396,136 further teaches "in situ" neutralization of thesulfonic acid polymer which, under some conditions, can result in theavailability of a small amount of polar cosolvent--i.e., a solvent forthe sulfonate groups about equal in amount to the amount of sulfonategroups which are present. This amount of polar cosolvent is not withinthe limits of the instant invention, which only optionally erequiresamounts of the third component (which interacts with the ionomericgroups of the ionomer copolymer) at levels whch range from 10 to 600times the molar equivalence of ionic groups. This level of cosolvent isabout one to two orders of magnitude or more higher than employed in thecited art. In addition, the cited patent is restricted to aromaticsulfonate polymers. The instant invention describes other polymers suchas sulfonated ethylene propylene terpolymers, sulfonated Butyl, etc.,which are a portion of the polymer complex.

U.S. Pat. No. 3,366,430 teaches the gelling of organic liquids by theinteraction of polar "associative bonds" which includes hydrogen bondingand "ionic cross-linking". Again, this patent specifies that twocomponents are necessary--the associating polymer (or polymers in somecases) and the nonpolar organic liquid. There is no mention of a thirdpolar cosolvent except to point out that such polar liquids should notbe present. Specifically, this patent states (Column 2, line 7) that thehydrocarbon liquids to which this invention is to be applied should notcontain a substantial portion of a miscible protolytic liquid such asmethanol. It is clear that the language of this patent limits thisinvention to gels and further, that any amount of polar liquids whichare present to an extent where they disrupt those gels are undesirable.The instant invention is distinct from that cited in that amounts ofsuch polar compounds, as will break up gel at ambient conditions, arerequired and in fact the most preferred state is free of any said gel atambient temperatures.

U.S. Pat. No. 3,679,382 teaches the thickening of aliphatic hydrocarbonswith synthetic organic polymers which contain olefinically unsaturatedcopolymerizable acids, amides, hydroxyacrylic esters, sulfonic acids,etc. It is emphasized in this patent (Column 3, line 72) that it iscritical that in the preparation of such polymers, no surface activeagent, catalyst or other additive be employed which introduces ametallic ion into the system. Therefore, it is preferred to employammonium or amine salts. It is clear that this invention (U.S. Pat. No.3,679,382) specifically precludes the use of metallic counterions--andis directed towards amine or ammonium derivatives. Only metalliccounterions are effective in the instant invention--and that, in fact,attempts to employ amine derivatives have not resulted in the resultswhich are the objectives of this invention. Finally, this cited patentdoes describe (Column 7, lines 13-19) that the addition of alcohols willreduce the viscosity of the thickened hydrocarbon and alter flowcharacteristics thereof.

U.S. Pat. Nos. 3,931,021 and 4,118,361 describe the use of ionicpolymers and required cosolvents in an organic liquid and V. I.Improvers. The instant invention represents an improvement over U.S.Pat. Nos. 3,931,021 and 4,118,361, and therefore provides a newdimension in viscosity control of hydrocarbon-based solvents.Specifically, it has been discovered that these complexes offer a"flatter" viscosity-temperature relationship than do the sulfonateionomers previously disclosed. Furthermore, the types of ionic polymerspreviously described as viscosifiers for oils and low polarity diluentsusually are effective thickeners at modest levels, but if one attemptsto make a concentrate (10% polymer by weight) the resulting solution istoo viscous to handle. The solutions described in this invention canhave relatively low viscosities at high concentrations of polymer, yetmaintain relatively high viscosities at low polymer concentrations. Thischange in the viscosity--concentration relationship is a fundamentaldiscovery of potentially great practical relevance.

SUMMARY OF THE INVENTION

It has been discovered that the viscosity of organic liquids may beconveniently controlled by incorporating in said organic liquid a minoramount of a polymer complex which is the reaction product of asulfonated polymer and a polymer containing low levels of nitrogenatoms. The polymer complex is characterized as having polymer backboneswhich are substantially soluble in the organic liquid, and pendantsulfonate groups which are substantially insoluble in the organicliquid.

The number of sulfonate groups contained in the sulfonated polymer ofthe polymer complex is a critical parameter affecting this invention.The number of sulfonate groups present in the polymer can be describedin a variety of ways such as weight percent, mole percent, number perpolymer chain, etc. For most polymer systems of interest in thisinvention, it is desirable to employ mole percent. For vinylhomopolymers, such as polystyrene, the sulfonated analog having asulfonate content of 1.0 mole percent means that one out of evey 100monomer repeat units in the polymer chain is sulfonated. In the case ofcopolymers, the same definition applied, except for the purposes of thiscalculation, the polymer can be considered to be prepared from ahypothetical monomer having an average molecular weight, which is theaverage of the two monomer components. Similarly for terpolymers, thesame averaging concepts apply; however, three components are involved.For example, ethylene-propylene-ethylidene norbornene (ENB) is apreferred polymer backbone for this invention. A representativeterpolymer would have a composition (weight percent) of 50% ethylene,45% propylene and 5% ENB. This composition has an average repeat unitmolecular weight of about 38.9. Thus, sulfonation of this composition,which occurs at the unsaturation of the ENB units to a level of 1.0 mole%, which means that in 38.9 gms (1 mole of average monomer repeat units)of this polymer, there would be present 0.01 mole of sulfonic acidgroups. An alternate way of expressing this is to state the sulfonatelevel in terms of milliequivalents of sulfonic acid groups per 100 gmsof polymer or meq. per 100 g. of polymer. This latter procedure providesa rapid and independent measure of sulfonic acid content in a polymerthrough simple titration.

Both mole percent sulfonate and milliequivalent of sulfonate will beemployed to describe the sulfonate polymers employed in this invention.

In general, the sulfonated polymer will comprise from about 4 meq. up to500 meg. of sulfonate groups per 100 g. of polymer, more preferablyabout 10 meq. to about 100 meq. of pendant sulfonate groups per 100 g.of polymer. Sulfonated polymers which are subject to the process of theinstant invention are illimitable and include both plastic andelastomeric polymers. Specific polymers include sulfonated polystyrene,sulfonated t-butyl styrene, sulfonated polyethylene, sulfonatedpolypropylene, sulfonated styrene/acrylonitrile copolymers, sulfonatedstyrene/methyl methacrylate copolymers, sulfonated block copolymers ofstyrene/ethylene oxide, acrylic acid copolymers with styrene, sulfonatedpolyisobutylene, sulfonated ethylenepropylene terpolymers, sulfonatedpolyisoprene, and sulfonated elastomers and their copolymers such asisoprene-styrene sulfonate copolymer or styrene/butadiene/metal styrenesulfonate terpolymers formed by a free radical copolymerization process.

The sulfonated polymers of the instant invention may vary in numberaverage molecular weight from 1,000 to 10,000,000, preferably 5,000 to500,000, most preferably from 10,000 to 200,000. These polymers may beprepared by methods known in the art; for example, see U.S. Pat. No.3,642,728, hereby incorporated by reference.

Neutralization of the cited sulfonated polymers with appropriate metalhydroxides, metal acetates, metal oxides, etc. can be conducted by meanswell-known in the art. For example, the sulfonation process as withButyl rubber containing a small 0.3 to 1.0 mole % unsaturation, can beconducted in a suitable solvent such as toluene with acetyl sulfate asthe sulfonating agent. The resulting sulfonic acid derivative can thenbe neutralized with a number of different neutralization agents such assodium phenolate and similar metal salts. The amounts of suchneutralization agents employed will normally be stoichiometrically equalto the amount of free acid in the polymer plus any unreacted reagentwhich still is present. It is preferred that the amount of neutralizingagent be equal to the molar amount of sulfonating agent originallyemployed plus 10% more to ensure full neutralization. The use of more ofsuch neutralization agent is not critical. Sufficient neutralizationagent is necessary to effect at least 50% neutralization of the sulfonicacid groups present in the polymer, preferably at least 90%, and mostpreferably essentially complete neutralization of such acid groupsshould be effected. The degree of neutralization of said ionomericgroups may vary from 50 to 500 mole %, preferably 90 to 200%. Mostpreferably, it is preferred that the degree of neutralization besubstantially complete, that is, with no substantial free acid presentand without substantial excess of the base other than that needed toensure neutralization. Thus, it is clear that the polymers which areutilized in the instant invention comprise substantially neutralizedpendant groups and, in fact, an excess of the neutralizing material maybe utilized without defeating the objects of the instant invention.

We have surprisingly found that a very important factor in determiningthe strength in the reaction product of the interaction between theamine-containing polymer and the sulfonate-containing polymer is thenature of the counterion. There are, broadly speaking, three majorclasses of such counterions. The first class, which are less preferred,are those metals of Group I and Group IIA, which include Li, Na, K,etc., Be, Mg, Ca, etc. We have found that these species do not interactas strongly with amine groups as the more preferred species describedbelow. Those metals are commonly defined as members of the transitionelements (see chemical text: "Chemical Principles and Properties", by M.J. Sienko and R. A. Plane, McGraw Hill Book Co., 1974, page 19). Thesemetal cations are best exemplified by zinc and interact strongly withpyridine and similar amines. As a consequence, a zinc neutralizedsulfonated polymer interacts much more strongly with a styrene/vinylpyridine copolymer than does a magnesium or sodium neutralized system.It is for this reason that the transition elements are preferred withzinc, copper, iron, nickel and cobalt being especially preferred. Wealso include antimony and lead as suitable cations.

A third species which is preferred is the free acid of the sulfonatedpolymer, which will also interact with amine-containing polymers. Inthis latter case, it is clear that the interaction is a classicacid-base interaction, while with the transition metals, a truecoordination complex is created, which is due to the donation of theelectron pair of the nitrogen element. This distinction is a veryimportant one and sets these complexes apart from classic acid-baseinteractions. The surprising observation is that such coordinationcomplexes can form in such extreme dilution insofar as interactinggroups are concerned, and that they are apparently formed so far removedfrom their expected stoichiometry, (based on small molecule analogs).

A variety of polymer backbones will display the desirable propertiesdiscovered in this invention:

    ______________________________________                                        Sulfonate Polymer  Amine Polymer                                              ______________________________________                                        Sulfonated EPDM    Styrene/Vinyl Pyridine                                     Sulfonate Isoprene Copolymer                                                  Copolymers         Vinyl Pyridine/Styrene/                                    Sulfonate Butadiene                                                                              Butadiene Terpolymers                                      Polymers           Isoprene/Vinyl Pyridine                                    Sulfonated Butyl   Copolymer                                                  Sulfonated Acrylate and                                                                          Ethylacrylate/Vinyl                                        Methacrylate Copolymers                                                                          Pyridine Copolymer and                                     Sulfonated Block Polymers                                                                        Alkyl Acrylate Copoly-                                     Sulfonated Polystyrene                                                                           mers with Vinyl                                            Sulfonated Poly-t-butyl                                                                          Pyridine, where the                                        Styrene            Alkyl group varies in                                      Sulfonate-containing                                                                             carbon number from 1 to                                    copolymers of the above                                                                          to 18                                                      systems            Methyl Methacrylate/-                                                         Vinyl Pyridine Pyridine                                                       Copolymer and Alkyl                                                           Methacrylate copolymers                                                       with Vinyl Pyridine,                                                          wherein the number of                                                         carbongroups in the                                                           alkyl group varies from                                                       1 to 18 carbon atoms.                                                         Butadiene/Vinyl Pyridine                                                      Copolymer                                                                     Propylene/Vinyl Pyridine                                                      Block Copolymer                                                               Ethylene/Vinyl Pyridine                                                       Block Copolymer                                                               t-Butyl Styrene/Vinyl                                                         Pyridine Copolymers                                                           Vinyl Pyridine Copoly-                                                        mers with alpha-beta                                                          ethylenically unsaturat-                                                      ed copolymers or ter-                                                         polymers.                                                  ______________________________________                                    

Preferably, the amine content in the basic polymer is expressed in termsof basic nitrogen. In this respect the nitrogen content in amides andsimilar nonbasic nitrogen functionality is not part of the interactingspecies. For example, the amount of vinyl pyridine in theamine-containing polymer can vary widely, but should range from lessthan 50 weight percent down to at least 0.5 weight percent of the weightof the total copolymer.

A minimum of three basic groups must be present on the average perpolymer molecule and the basic nitrogen content generally will rangefrom 4 meq. per 100 grams of polymer up to 500 meq. per 100 g. A rangeof 8 to 200 meq. per 100 g. is preferred.

It is evident that the water insoluble sulfonated polymers coveredwithin this invention encompass a broad class of hydrocarbon polymersystems. It is important that these hydrocarbon polymer backbones (inthe absence of the sulfonate groups) be soluble in the organic liquid,whose viscosity is to be controlled. To achieve the desired solubility,it is required that the polymer to be employed possess a degree ofpolarity consistent with that solvent. This solubility relationship canbe readily established by anyone skilled in the art simply byappropriate texts (e.g., Polymer Handbook, edited by Brandrup andImmergut, Interscience Publishers, 1967, section IV-341). In the absenceof appropriate polymer solvent compatibility knowledge, this can bedetermined experimentally by observing whether the selected polymer willbe soluble in the solvent at a level of 1 gm polymer per 100 ml solvent.If the polymer is soluble, then this demonstrates that it is anappropriate backbone for modification with sulfonate groups to achievethe objectives of this invention. It is also apparent that polymerswhich are too polar will not be soluble in the relatively nonpolarorganic liquids of this invention. Therefore, only those polymerbackbones (i.e., as measured in the absence of ionic groups) having asolubility parameter less than 10.5 are suitable in this invention. Thisprecludes the use of such polymers as polyvinyl alcohol,polyacrylonitrile, etc. Also highly crystalline polymers are to beavoided since they tend not to be soluble in the relatively nonpolarorganic liquids employed herein. Therefore, acceptable polymers employedin this invention must possess a level of crystallinity of less than25%. Thus, these acceptable polymers can be considered substantiallynoncrystalline.

The preferred ionic EPDM terpolymers for use in the instant inventionare prepared by sulfonation of an EPDM-containing ethylidene norborneneunits. Other specific examples of preferred ionomeric polymers which areuseful in the instant invention include sulfonated polystyrene,sulfonated poly-t-butyl styrene, sulfonated polyethylene, (substantiallynon-crystalline) and sulfonated polyethylene copolymers, sulfonatedpolypropylene (substantially noncrystalline), and sulfonatedpolypropylene copolymers, sulfonated styrenemethyl methacrylatecopolymers, (styrene)acrylic acid copolymers, sulfonatedpolyisobutylene, sulfonated ethylenepropylene terpolymers, sulfonatedpolyisoprene, sulfonated polyvinyl toluene, sulfonated polyvinyl toluenecopolymers and isoprene-styrene sulfonate copolymers formed by a freeradical copolymerization process.

The ionomeric polymers of the instant invention may be neutralized priorto incorporation into the organic solvent, or by neutralization of theacid form in situ. For example, preferably the acid derivative isneutralized immediately after preparation. For example, if thesulfonation of polystyrene is conducted in solution, then theneutralization of that acid derivative can be conducted immediatelyfollowing the sulfonation procedure. The neutralized polymer may then beisolated by means well-known to those skilled in the art; i.e.,coagulation, stream stripping, or solvent evaporation, because theneutralized polymer has sufficient thermal stability to be dried foremployment at a later time in the process of the instant invention. Itis well-known that the unneutralized sulfonic acid derivatives do notpossess good thermal stability and the above operations avoid thatproblem.

The water insoluble basic nitrogen-containing polymer such asstyrene-vinyl pyridine copolymer of the water insoluble polymer complexis formed by free radical copolymerization using techniques well-knownin the polymer literature. Such polymers can be prepared by a variety oftechniques by reacting a basic nitrogen-containing monomer withalpha-beta ethylenically unsaturated monomers such as styrene, t-butylstyrene, alkyl acrylates, alkyl methacrylates, butadiene, isoprene vinylchloride, acrylonitrile, acrylonitrile/butadiene/styrene monomermixtures and copolymers, or more complex mixtures. An emulsionpolymerization process is generally preferred, but other processes arealso acceptable.

The polymer complex of the sulfonated polymer and the basicnitrogen-containing polymer can be formed by forming a first solution ofthe sulfonated polymer in an organic liquid and a second solution of thebasic nitrogen-containing polymer in the organic liquid, wherein theorganic liquid which has a solubility parameter of less than 9.5, asmeasured at 25° C., and a viscosity of less than about 200 centipoisesand is selected from the group consisting of mineral oil, synthetic oil,naphthanes, alkanes, cycloalkanes and aromatic hydrocarbons and mixturesthereof. Alternately both components of the complex can besimultaneously dissolved in the same solvent systems at the desiredconcentrations. The concentration of the sulfonated polymer in the firstsolution is about 0.05 to about 10 grams per 100 ml of organic liquid,more preferably about 0.1 to about 5. The concentration of the basicnitrogen-containing polymer in the second solution is about 0.05 toabout 10 grams per 100 ml of the organic liquid, more preferably about0.1 to about 5, and most preferably about 0.1 to about 2. The twosolutions of the sulfonated polymer and the basic nitrogen-containingpolymer are mixed together to form the polymer complex, wherein eitherthe sulfonated polymer or the basic nitrogen-containing polymer such astyrene-vinyl pyridine copolymer can be substantially in excess of theother. The formation of the complex is schematically represented by:##STR2##

The presence of an excess of one component over the other offers aunique opportunity to alter the viscosity-temperature profiles of suchsolutions. In the creation of the complex a combination of two polymersinteracting with an excess of one (such as the styrene/vinyl) pyridinecopolymer), we have created a complex which is, in turn, plasticized.Such a system will display modest viscosity at low or ambienttemperatures: ##STR3## The application of heat to the right-hand side ofEquation 2 would be expected to shift the equilibrium modestly to theleft. Consequently, the higher viscosity complex would be favored with apotential increase in solution viscosity.

The weight ratio of the neutralized sulfonated polymer to the aminecontaining polymer which contains basic nitrogen groups is about 20/1 toabout 1/20.

The polymer complex can be formed in situ by mixing together thesolutions of zinc sulfo-EPDM in organic liquid and the solution ofstyrene-vinylpyridine copolymer in organic liquid or, alternatively, thepolymer complex can be dissolved into the organic liquid.

Thus, this concept describes the interaction of two polymers which cangive rise to new solution phenomena. A second consequence of thisconcept is that if such solutions are diluted with non-interactive (lessinteractive) solvent, such as mineral oil or similar low polaritydiluents, the result will be a dimunition of the plasticizer componentwith a relative increase in complex viscosity. Thus, unlike normalpolymer solutions which drop off dramatically upon dilution, thesesolutions may decrease much less in their solution viscosity. Suchhydrocarbon or oil solutions have not been available previously. Theconcentration of the polymer complex in the organic liquid is about 0.05to about 20 grams per 100 ml, more preferably about 0.1 to about 10, andmost preferably about 0.2 to about 10.

The method of the instant invention includes optionally incorporating acosolvent, for example, a polar cosolvent, into the mixture of organicliquid and polymer complex, to solubilize the pendant sulfonate groups.The polar cosolvent will have a solubility parameter of at least 10.0,more preferably at least 11.0, and may comprise from 0.1 to 40,preferably 0.5 to 20 weight percent of the total mixture of organicliquid, ionomeric polymer, and polar cosolvent wherein the polarcosolvent is selected from the group consisting of alcohols and amines.

In addition to the requirements for ionic polymer, organic liquid andpolar cosolvent, there is the additional and important constraint thatthe polar cosolvent be more polar than the organic liquid. This isrequired in order that the proper interaction between polar cosolventand ionic groups be obtained. If we designate the solubility parameterof the organic liquid as S_(L), and the solubility parameter of thepolar cosolvent as Sp, then we require that:

    S.sub.p ≦S.sub.L +1.0

In other words, the polar cosolvent will be substantially more polarthan the organic liquid to be thickened.

Normally, the polar cosolvent will be a liquid at room temperature,however, this is not a requirement. It is required that the polarcosolvent be soluble or miscible with the organic liquid at the levelsemployed in this invention. Under normal circumstances, this miscibilityrequirement precludes the use of water as a polar cosolvent. The polarcosolvent must be present in amounts of from 10 to 600 moles per mole ofionic group in order to give the desirable results of the instantinvention and preferably from 20 to 400 moles per mole of ionic group.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following are preferred embodiments of the instant invention.

EXAMPLE 1 Preparation of Styrene-4-Vinyl Pyridine Copolymer

A copolymer of styrene-4-vinyl pyridine was prepared via a free radicalemulsion copolymerization process. The preparation was conducted asfollows:

In a suitable, stirred reaction vessel under a nitrogen blanket thefollowing ingredients were charged:

120 ml. distilled water

50 g. styrene

3.2 g. sodium lauryl sulfate

0.1 g. dodecylthiol

0.2 g. potassium persulfate

4.7 g. 4-vinyl pyridine.

The polymerization was conducted at 50° C. for 24 hours and theresultant emulsion was fluid and uniform. Three ml. of methanolcontaining 0.1% of hydroquinone was added as an inhibitor and thereaction mixture was precipitated in a large excess of acetone. Theprecipitate was filtered, then suspended in methanol and blended in aWaring blender to finally disperse the coagulated polymer. Thesuspension was filtered and dryed in a vacuum oven at 60° C. for 24hours.

The resulting product represented 80% conversion of the reactivemonomers and contained 1.68% nitrogen corresponding to 12.5 mole %4-vinyl pyridine incorporation.

EXAMPLE 2 Preparation of Sulfonated EPDM

The preparation of sulfonated EPDM has been well-described in the patentand published literature (for example, see U.S. Pat. No. 4,184,988 orACS Monograph edited by A. Eisenberg, 1980, p. 4). A zinc sulfonatedEPDM was prepared via those procedures containing 10 meq. of zincsulfonate, designated TP 398. The resulting polymer was available as afree-flowing crumb and employed in that form as a blending component inthe following examples.

EXAMPLE 3 Preparation of Polymer Complex

The polymer complex of sulfonated EPDM and polystyrene-Co-4-vinylpyridine is prepared by charging the required amounts of each polymer toa flask, adding xylene in sufficient quantity to produce the desiredconcentration and stirring at room temperature until a homogeneoussolution is obtained. This generally requires from 2 to 24 hoursdepending on the concentration required.

EXAMPLE 4 Comparision of Polymer Complex, Sulfonated EPDM and EPDMSolution Viscosity as a Function of Temperature, With and Without theAddition of Polar Solvent

Solutions were prepared as described in Example 3 of the sulfonated EPDM(10 meq. zinc sulfate)-polystyrene-Co-4-vinyl pyridine complex,sulfonated EPDM (10 meq. sulfonate) and EPDM (backbone EPDM used toprepare the sulfonated EPDM). Viscosity measurements were measured atvarious temperatures using a Brookfield Viscometer over a range of 0° to120° C., for each solution. To measured volumes of each solution,various levels of hexanol were added and viscosity vs. temperatureobtained. The data are summarized in Table I. The viscosity of thesulfonated EPDM solution shows a marked decrease with increasingtemperature. The viscosity of the polymer complex solution shows a muchflatter (more isoviscous) temperature relationship. The addition ofhexanol to the complex provides an even more temperature insensitiveprofile. It is important to note that in all cases, the complex behavesquite differently from the sulfonated EPDM-based solutions in terms ofthe viscosity-temperature relationships.

EXAMPLE 5 Comparison of Polymer Complex and Sulfonated EPDM SolutionViscosity As A Function of Concentration

Solutions were prepared as described in Example 3 of 5% concentration ofsulfonated EPDM (10 meq. of zinc sulfonate per 100 g.) in xylene; 5%sulfonated EPDM plus 0.6% polystyrene-Co-4-vinyl pyridine in xylene(Comlex A); and 5% sulfonated EPDM plus 1.2% polystyrene-Co-4-vinylpyridine in xylene (Complex B). Viscosity measurements at 25° C. wereobtained of each solution and of xylene dilutions, as noted in Table II.

The data of Table II show that at high concentrations, the solutionscontaining the complex have relatively lower viscosities as compared tosolutions of sulfonated EPDM. On the other hand, the solutionscontaining the complex maintain higher viscosities at lowerconcentrations.

These results are very critical for the following reasons. While ionomersolutions, such as sulfonated EPDM in oil or other hydrocarbons, arevery effectively viscosified at high polymer levels (i.e., >1 or 2%)this very characteristic gives rise to solutions at high polymer levels(5 to 10%) which are too viscous to handle. Yet when such polymers arediluted to low polymer levels (≦1%) the viscosity decreases very rapidlyand actually becomes less than that of a polymer without ionic groups.Technologically, this is a major deficiency since it is desirable tohave viscosification at a very low polymer level. It is evident from thedata in Table II that the polymer complexes perform that function. As aconsequence, the very desirable result is that the solution viscosity ofthese polymer complexes can be less variant with polymer concentrationthan almost any other viscosification approach. Furthermore, the ratiosof the polymer components can be altered to vary theviscosity-concentration of the polymer solution at will.

As an example, the data in Table II show that the viscosity ofsulfonated EPDM solution at the 5% level is 9.55×10⁵ cp., while at 1.5%that value is 46 cp, a change of about 20,000. In contrast, the complex,at comparable polymer levels, (4% sulfonated EPDM+0.96% styrene-vinylpyridine copolymer) exhibits a viscosity of 8000 cp. The same complex,at a total polymer level of only 1.24%, exhibits a viscosity of 35 cp.,a change of only a factor of 2,000. It is clear that the change of thesolution viscosity of the complex is a factor of 100 less than that ofthe sulfonate ionomer.

The explanation for this novel behavior is that the ionomer viscosity,at high concentrations, is attributable to interpolymer associations,while at low concentrations, intraassociations occur, which are noteffective in viscosification. The complex, however, markedly enhancesinterpolymer associations, even at dilute polymer levels, and viscosityis thereby enhanced.

EXAMPLE 6 Polymer Complex With Higher Molecular WeightPolystyrene-Co-4-Vinyl Pyridine. Comparing Polymer Complex, SulfonatedEPDM and Polystyrene-Co-4-Vinyl Pyridine Viscosity as a Function ofConcentration

A higher molecular weight copolymer of styrene and 4-vinyl pyridine wasprepared in a similar manner described in Example 1, by deleting thedodecylthiol from the reaction ingredients.

The resulting product contained 1.13% nitrogen corresponding to 8.4 molepercent 4-vinyl pyridine incorporation.

Solutions were prepared in xylene, as described in Example 3, of thishigher molecular weight polystyrene-Co-4-vinyl pyridine, and a complexcontaining 3% (by weight) sulfonated EPDM (10 meq. zinc sulfonate) and0.72% (by weight) of the polystyrene-Co-4-vinyl pyridine. Viscositymeasurements at 25° C. were obtained for each solution of xylenedilutions as noted in Table III.

                                      TABLE I                                     __________________________________________________________________________    Solution Viscosity of Polymer Components and Complexes                        With and Without Polar Cosolvent in Xylene                                               %    % Sytrene-                                                    Sample                                                                            EPDM   EPDM Co-4-Vinyl                                                                          %    Viscosity (CP) at Temperature (°C.)         9234-                                                                             Polymer                                                                              Polymer                                                                            Pyridine                                                                            Hexanol                                                                            0  25 50 75 100                                                                              120                                 __________________________________________________________________________    A   EPDM   1.5  0.5   --   5.20                                                                             3.48                                                                             2.56                                                                             2.00                                                                             1.60                                                                             1.40                                B   EPDM   1.5  0.5   2    5.00                                                                             3.30                                                                             2.32                                                                             1.84                                                                             1.46                                                                             1.30                                C   10 meq.                                                                              1.5  --    --   5,000                                                                            135                                                                              20 7.80                                                                             4.50                                                                             3.39                                    Sulfo-EPDM                                                                D   10 meq.                                                                              1.5  --    2    6.96                                                                             4.96                                                                             4.05                                                                             3.40                                                                             2.85                                                                             2.37                                    Sulfo-EPDM                                                                E   10 meq.                                                                              1.5  0.5   --   352                                                                              166                                                                              95 51 27.3                                                                             15.3                                    Sulfo-EPDM                                                                F   10 meq.                                                                              1.5  0.5   0.5  202                                                                              127                                                                              76 43 23.8                                                                             14.2                                    Sulfo-EPDM                                                                G   10 meq.                                                                              1.5  0.5   1    83.5                                                                             75.4                                                                             56 36.3                                                                             21.5                                                                             13.6                                    Sulfo-EPDM                                                                H   10 meq.                                                                              1.5  0.5   2    30.2                                                                             31.9                                                                             29.3                                                                             23.3                                                                             16.1                                                                             10.5                                    Sulfo-EPDM                                                                __________________________________________________________________________

                                      TABLE II                                    __________________________________________________________________________    Solution Viscosity of Polymer and Sulfonated                                  EPDM as a Function of Concentration                                           Sulfo-EPDM Complex A - Sulfo-EPDM+                                                                      Complex B - Sulfo EPDM+                               (10 meq, TP398)                                                                        % P--Sty--CO--4                                                                         Viscosity                                                                          % P--Sty--Co--4                                                                         Viscosity                                 % Viscosity, cp                                                                          Vinyl Pyridine                                                                          cp.  Vinyl Pyridine                                                                          cp                                        __________________________________________________________________________    5 955,000  0.6       120,000                                                                            1.2       13,000                                    4 700,000  0.48      48,000                                                                             0.96      8,000                                     3 247,000  0.36      39,000                                                                             0.72      5,000                                     2 5,000    0.24      10,000                                                                             0.48      1,400                                     1.5                                                                             46       0.18      2,100                                                                              0.36      490                                       1 5        0.12      25   0.24      35                                        __________________________________________________________________________

                                      TABLE III                                   __________________________________________________________________________    Solution Viscosity of High Molecular Weight Polystyrene-Co-- 4-Vinyl          Pyridine                                                                      Sulfonated EPDM and Polymer Complex as a Function of Concentration            Sulfo EPDM  High Molecular Weight                                                                        Sulfo-EPDM, High M.W.                              10 meq. Zinc Sulfonate                                                                    P--Sty--Co--4-Vinyl Pyridine                                                                 P--Sty--Co--4-Vinyl Pyridine Complex               %   Viscosity, cp                                                                         %    Viscosity, cp                                                                           % Sulfo EPDM                                                                          % P--Sty--CO--4VP                                                                        Viscosity,                      __________________________________________________________________________                                                  cp                              5   955,000 3    310       3       0.72       1,650,000                       4   700,000 2    70        2       0.48       680,000                         3   247,000 1    10.5      1       0.24       160,000                         2   5,000   0.5  3.5       0.5     0.12       7,200                           1.5 46      0.25 1.8       0.25    0.06       15.6                            1.0 5                                                                         __________________________________________________________________________

These data convincingly demonstrate that a combination of the copolymerof styrene and 4-vinyl pyridine with the zinc sulfo EPDM provides asolution whose viscosity is much enhanced over that of either componentpolymer even though the complex is lower in concentration. For example,the sulfo EPDM solution has a viscosity of about 5 cp at 1% polymer, thestyrene vinyl pyridine copolymer has a viscosity of 10.5 cp at that sameconcentration, while the complex exhibits a viscosity of over 7000 cp ata total polymer concentration of 0.62%.

Clearly, the complex, even at very dilute concentrations, is a moreeffective thickening system for hydrocarbon fluids. There are otherunique characteristics of these solutions as well, but more importantlythese data demonstrate that the complex provides enhanced intermolecularassociations and minimizes the intramolecular associations which arecounterproductive in the thickening efficiency of the Sulfo EPDMsolutions.

Since many modifications and variations of this invention may be madewithout departing from the spirit or scope of the invention thereof, itis not intended to limit the spirit or scope thereof to the specificexamples thereof.

What is claimed is:
 1. A method for controlling the viscosity of organicliquids, said organic liquid having a solubility parameter of less than9.5, a viscosity, as measured at 25° C., of less than 200 centipoisesand said organic liquid is selected from the group consisting ofalkanes, cycloalkanes and aromatic hydrocarbon and mixtures thereof,which comprises incorporating in said organic liquid about 0.01 to 20grams of a polymer coordination complex per 100 ml. of said organicliquid, said polymer coordination complex being comprised of polymer A,containing neutralized sulfonate groups, and polymer B, containing basicnitrogen groups, the functional groups of both polymer A and polymer Bbeing each present at a level of from about 4 to 500 meq. per 100 g. ofpolymer, wherein polymer B has the formula: ##STR4## wherein x is about50.0 to 99.8 weight percent and y is about 0.2 to about 50.0 weightpercent, wherein said sulfonate groups of said polymer A beingneutralized with a transition metal ion, said polymer A having apolymeric backbone having a solubility parameter of less than 10.5 andsaid polymer A having a number average molecular weight of about 1,000to 10,000,000 wherein a weight ratio of polymer A to polymer B is about20/1 to 1/20.
 2. The method of claim 1, further including a polarcosolvent, wherein said polar cosolvent comprises from about 0.1 to 40weight percent of the total mixture of said organic liquid, said polymercoordination complex and said polar cosolvent, wherein the solubilityparameter of the polar cosolvent is at least one unit greater than thesolubility parameter of said organic liquid.
 3. The method of claims 1or 2, wherein said organic liquid has a viscosity at 25° C. of less than200 centipoises.
 4. The method of claims 1 or 2, wherein said organicliquid is a synthetic oil.
 5. The method of claims 1 or 2, wherein saidsulfonated polymer is a sulfonated EPDM terpolymer.
 6. The method ofclaims 1 or 2, wherein said sulfonated polymer is selected from thegroup consisting of sulfonated ethylene, sulfonated propylene,sulfonated ethylene-propylene copolymers and terpolymers, wherein thethird monomer is a nonconjugated diene hydrocarbon having from 5 to 15carbon atoms and sulfonated polystyrene.
 7. The method of claim 2,wherein said polar cosolvent is an alcohol.
 8. The method of claim 2,wherein said polar cosolvent has a boiling point of at least 50° C.
 9. Acomposition of matter which is a polymer coordination complex which isthe reaction product of a sulfonated polymer containing about 4 to about500 meq. of neutralized sulfonate groups per 100 grams of sulfonatedpolymer and a basic nitrogen-containing polymer, said basic nitrogencontaining polymer having the formula: ##STR5## wherein x is about 50.0to 99.8 weight percent and y is about 0.2 to about 50.0 weight percent,wherein said sulfonate groups of said sulfonated polymer beingneutralized with a transition metal ion, said sulfonated polymer havinga polymeric backbone having a solubility parameter of less than 10.5 andsaid sulfonated polymer having a number average molecular weight ofabout 1,000 to 10,000,000.
 10. The composition of claim 9, wherein saidamine-containing polymer is a copolymer of styrene-vinylpyridine. 11.The composition of claim 9, wherein said sulfonated polymer is asulfonated EPDM terpolymer.
 12. The composition of claim 9, wherein saidsulfonated polymer is selected from the group consisting of sulfonatedethylene, sulfonated propylene, sulfonated ethylene-propylene copolymersand terpolymers, wherein the third monomer is a nonconjugated dienehydrocarbon having from 5 to 15 carbon atoms and sulfonated polystyrene.